1. Field of the Invention
The present invention relates to heavy duty liquid (HDL) compositions which contain both proteolytic enzymes and peroxygen bleach. In particular, the invention relates to HDL compositions in which enzyme stability is maintained without at the same time sacrificing peroxygen bleach stability. The invention further relates to methods of improving peroxygen bleach stability in HDL compositions containing proteolytic and lipolytic enzymes.
2. Prior Art
A peroxygen bleach compound in a heavy duty liquid composition which contains no enzymes stabilizers will remain relatively stable although, of course, the stability of enzymes present in such compositions is seriously compromised. While the addition of enzyme stabilizers increases the stability of the enzymes present, the enzyme stabilizers will simultaneously decrease the stability of peroxygen bleach compounds in the composition.
The addition of a glycerol/borate stabilization system to compositions containing both enzymes and peroxygen bleach, for example, results in compositions having good enzyme stability but poor peroxygen bleach stability.
Unexpectedly, applicants have found that using proteins having a molecular weight under 50,000 as stabilizers in HDL compositions containing peroxygen bleach help to stabilize the enzyme while simultaneously destabilizing the peroxygen bleach to a much lesser extent relative to the peroxygen bleach destabilization caused by other enzyme stabilizers, e.g., glycerol.
In a second embodiment of the invention, applicants have found that specific carboxylic acid enzyme stabilizers (e.g. acetic acid, propionic acid, adipic acid) are far superior compared to formic acid stabilizer, for example, in their ability to stabilize enzymes while remaining far less harsh on peroxygen bleach (i.e. causing far less peroxygen bleach destabilization).
The prior art includes many examples of enzyme stabilizers, including the use of carboxylates and proteins as stabilizers. For example, the use of carboxylates as stabilizers is disclosed in U.S. Pat. No. 4,243,546 to Shaer, U.S. Pat. No. 4,318,818 to Letton et al., and U.S. Pat. No. 4,518,694 to Shaer; while the use of proteins as stabilizers disclosed in U.S. Pat. No. 4,842,758 to Crutzen et al., U.S. Pat. No. 4,842,767 to Warshewski et al., U.S. Pat. No. 3,560,392 to Eymery et al., U.S. Pat. No. 3,296,094 to Cayle and U.S. Pat. No. 3,325,364 to Merritt et al.
In none of these references, however, is there disclosed the use of either proteins having a molecular weight below 50,000 or specific carboxylate compounds in compositions comprising peroxygen bleach; or is there any recognition that these specific stabilizers can stabilize enzymes while having little or no effect on peroxygen bleach stability.
In applicants copending U.S. Ser. No. 592,942, the use of quaternary nitrogen compounds for enzyme stabilization is disclosed. There is no teaching or suggestion that proteins having a molecular weight under 50,000, particularly cationic proteins, may be used in compositions also comprising peroxygen bleach or that these stabilizers are far less harsh on peroxygen bleach than other enzyme stabilizers, e.g., glycerol.
In European Publication No. 378,261 (Procter & Gamble), the use of peroxygen bleach in combination with formate, acetate, or propionate is disclosed in the examples. There is no indication at all from this reference that the use of acetate, propionate or adipate greatly enhances both enzyme and bleach stability (e.g., relative to glycerol) or that bleach stability using formate is far inferior to bleach stability using acetate, propionate or adipate.
European Publication No. 293,040 (Procter & Gamble) teaches compositions using peroxygen bleach and formate. Again, there is no teaching or suggestion that acetate, propionate or adipate is far superior to formate in terms of stabilizing enzyme without simultaneously destabilizing peroxygen bleach. Further it is not clear from this reference that formate is used to stabilize both the enzyme and the bleach. Rather, stabilization of peroxygen bleach is apparently accomplished using a solvent system comprising water and a water-miscible solvent.
In short, the art fails to recognize that specific protein stabilizers may be used to stabilize enzymes while providing little or no peroxygen bleach destabilization; or that specific carboxylate stabilizers (e.g., acetate, propionate or adipate) are far superior than others (i.e., formate) for stabilizing both enzymes and peroxygen bleach in HDLs.